Silicon carbide materials are useful in many applications, including, for example, armor, solid state semiconductor materials, and various nuclear applications. Silicon carbide materials with a high theoretical density may exhibit a high hardness and are, therefore, suitable in applications such as, for example, military grade body armor or in armored vehicles. However, silicon carbide is a difficult material to sinter and, therefore, fabrication of materials including silicon carbide is difficult. In addition, silicon carbide structures having nonconventional geometries are difficult to fabricate.
Spark plasma sintering (SPS) is a method of sintering a powdered material by directing electric current in pulses to a powder loaded in a die. Small scale spark plasma sintering of silicon carbide conventionally uses sintering aids and other additives to facilitate sintering of the silicon carbide material. However, as the size of the structure to be sintered increases, it is increasingly difficult to form the silicon carbide structure to near full theoretical density by spark plasma sintering. For example, as the size of the structure increases, it is difficult to uniformly distribute heat to the powder loaded in the compacted die of the spark plasma sintering tool. Accordingly, the sintered silicon carbide structure may exhibit nonuniform properties (e.g., hardness and density) across a cross-section thereof.
Conventional methods of fabricating silicon carbide structures (e.g., silicon carbide tiles) used for armor and related applications include liquid phase sintering, solid state sintering, hot isostatic or axial pressure sintering, pressureless sintering, or other sintering methods. Such methods are time consuming, consume more power than spark plasma sintering, and are expensive. In addition, sintering silicon carbide using such techniques often uses excessive amounts of sintering aids to enhance diffusion and sintering. For example, structures formed by solid state sintering or liquid phase sintering may include between about 0.5 weight percent and about 3.0 weight percent or between about 5 weight percent and about 15 weight percent of sintering aids, respectively. However, such sintering aids may reduce one or more of a purity, a density, a hardness, or a strength of the sintered structure.